I. Field of the Invention
This invention relates generally to a system and related method for inspecting an object, and more specifically, a system and related method for radiographically inspecting an object, positioned at a selected inspecting location, using backscattered radiation to generate a radiographic image of the object.
II. Background Information
Systems and techniques are known for radiographically inspecting an object using radiation directed to, and passing through, the object. Such systems typically use a radiation source to generate radiation and to direct the radiation along a radiation path toward a selected inspecting location at which the object is positioned. Detectors, disposed in the radiation path, beyond the selected inspecting location, are operative to detect the radiation passing through the object and to generate signals in response to the "through radiation." The through radiation, which has been attentuated by the object, and the signals generated in response to the attenuated, through radiation provide a representation of the object for use in generating a radiographic image.
Certain known radiographic inspection systems further include "backscatter detectors" disposed in the radiation path between the radiation source and the selected inspecting location. These "backscatter detectors" detect radiation interactive with and "backscattered" by an object at the selected location, and generate signals in response to the detected radiation. That is, the "backscatter detectors" detect, and generate response signals for, radiation traveling "backward" from an object as a result of compton scattering or photoelectric fluorescence. Such inspection systems, having detectors which detect both the radiation passing through and "backscattered" by an object at the inspecting location, provide an improved image of the object.
Although an improved image is obtained when through and backscattered radiation are detected utilizing both through radiation and backscatter detectors, the need often arises to exclude through radiation detectors from radiographic inspection systems. Notwithstanding the useful representational information provided by through radiation detectors, the limited amount of space available for the inspection system, or the particular nature or location of the object to be inspected, may make the placement of through radiation detectors beyond the inspecting location impossible or extremely difficult. This is often the case where the object to be inspected is an object like a wall, large box or container, or a large structure like an aircraft wing or fuselage.
Typically, in such instances, a representation of the object is obtained using only backscatter detectors and the radiation backscattered by the object. No account of the radiation passing through the object is taken. Accordingly, the quality of the image suffers as compared with the image obtained when both through radiation and backscatter detectors are used.
Conventional inspection systems which rely only on backscattered radiation to obtain a representation of the object do not include apparatus or methods for significantly improving the representation of the object beyond the quality of image obtained when only response signals generated from backscatter radiation are used.